From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: <9front-bounces@9front.inri.net> X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-1.1 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI autolearn=ham autolearn_force=no version=3.4.4 Received: from 9front.inri.net (9front.inri.net [168.235.81.73]) by inbox.vuxu.org (Postfix) with ESMTP id 080992865C for ; Mon, 5 Aug 2024 01:01:58 +0200 (CEST) Received: from mimir.eigenstate.org ([206.124.132.107]) by 9front; Sun Aug 4 19:00:00 -0400 2024 Received: from mimir.eigenstate.org (localhost [127.0.0.1]) by mimir.eigenstate.org (OpenSMTPD) with ESMTP id 6bab1dd4 for <9front@9front.org>; Sun, 4 Aug 2024 15:59:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=eigenstate.org; h= message-id:to:subject:date:from:in-reply-to:mime-version :content-type:content-transfer-encoding; s=mail; bh=gOfWXW3JxJyT mc6S5IGLegoc6OI=; b=i0ZrVUwNCaYUJMzwLAPbT3+knir1WdOyaqEchy5J5Eii Nlha5Zx6Z5yP0VFhoeDeTj46sd3YPR67QijWijXfhvqsByub7Mv8Zn8ttspUaVl8 kZttsEWjTisVTxKz0I8OHmpeeIH9qY/QFYnUf53/WO8DAkPuFDhb4NatxoJCz04= DomainKey-Signature: a=rsa-sha1; c=nofws; d=eigenstate.org; h=message-id :to:subject:date:from:in-reply-to:mime-version:content-type :content-transfer-encoding; q=dns; s=mail; b=lRbiOBBuHhSy8UQ2HN+ CVFH9ua7ehOTcJPnSKHxOR4XmaiuQ03w1ibQx2vE4is0uLDgcr1KBQFtI7Jaev1F jzu5k0MVzJoAb3JvNOYSfN6aL/6n2M/EiGKdVUAZgq4JaGBvANPfV2jpNd9gKdw2 Lop6348sl9QXfPmM85v7IOMY= Received: from chainsaw.dev ( [172.58.160.34]) by mimir.eigenstate.org (OpenSMTPD) with ESMTPSA id f0d709bf (TLSv1.2:ECDHE-RSA-AES256-SHA:256:NO) for <9front@9front.org>; Sun, 4 Aug 2024 15:59:58 -0700 (PDT) Message-ID: To: 9front@9front.org Date: Sun, 04 Aug 2024 18:57:16 -0400 From: ori@eigenstate.org In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit List-ID: <9front.9front.org> List-Help: X-Glyph: ➈ X-Bullshit: asynchronous webscale enhancement-based injection generator Subject: Re: [9front] Thoughts on Wayland? Reply-To: 9front@9front.org Precedence: bulk Quoth David Leimbach : > > Sent from my iPhone > > > On Aug 4, 2024, at 3:28 PM, ori@eigenstate.org wrote: > > > > Quoth David Leimbach : > >> > >>> > >>>> > >>>> While it's theoretically possible to do mmap over 9p, it's not going to > >>>> be a good experience. > >> > >> Is it substantially worse than mmap’ing over NFS? I can imagine a lot of panic or deadlock cases but…. Yeah that’s true for NFS also. At least a core dump. > >> > > > > I'm not familiar enough with the internals of the NFS > > protocol to say for sure. > > > > However, dont' just consider deadlock, consider coherence. > > What happens if you put a mutex into shm, and two machines > > try to lock it at the same time? > > > > How do you avoid turning every single memory access into > > a network round trip without some sort of sideband protocol? > > > > What happens if a laptop participating in that coherence > > mechanism gets its lid closed and hibernates for an hour or > > three, and then comes back? > > > It’s a nasty game of timeouts and hangups… like everything in distributed systems. > ah, except in a distributed system, locks are provably broken; they can't even work in theory. Imagine two cases: 1) a machine takes a lock, pauses for an arbitrary amount of time, and then tries to proceed with its critical section, assuming that nobody has mutated its state 2) a macine takes a lock, and then dies permanently, never to return. you can do one of two things here: you can either time out the lock, or hold it forever. in case 1, if you hold it forever, the system is correct. If you time it out, you've just done critical work outside a critical section and corrupted data. in case 2, if you hold it forever, you have a deadlock that can't be recovered from; the machine is never coming back. you need a correct distributed system to obey wait-free like properties. sofware needs to be designed from the ground up to be aware of the complexity of distributed systems; if you try to take a system that was designed to run on a single failure domain and make it distributed by layering over something like mmap, either things get very complex, or they get very broken; that is not an exclusive or.